مجله مهندسی ساخت و تولید ایران
سال ششم شماره 9 (اسفند 1398)

A manufacturing route is defined for any product in all of the manufacturing workshops and the factories. Since, different numbers of processes are conducted on a product, the processing routes are saved on some manual sheets. These sheets show the details of process planning for any product during the manufacturing route. By entering the computers to industry, the route sheets started to be produced using of the computers. Moreover, some software's were developed to automatically produce the process planning programs which are known as Computer Aided Process Planning (CAPP) systems. In this research, a CAPP based software is developed for feature recognition and extraction of the cylindrical parts to provide the raw data of the CAPP systems. On the other hand, except for the feature extraction of cylindrical parts, this program is be able to create the process planning program in a semiautomatic manner using of its extracted feature data. After recognition and extraction of the features, the parts are classified and are compared with the created data base features and one or more process planning program is suggested finally. Also, the new parts again can be saved for using in the program data base. This program results were compared with a different number of created process planning route sheets and the results confirmed the program reliability. Therefore, this program can be used in machining workshops with a high accuracy.

The equal channel angular rolling (ECAR) process is one of the methods of severe plastic deformation that is considered to obtain ultrafine-grain materials (UFG.( In this study, the effect of temperature on the mechanical properties of 5083 aluminum alloy was investigated in this process. Equal channel angular rolling process was performed at the temperatures 25℃ (room temperature), and 200 and 300℃. The equal channel angular rolling was used as a lubricant. The evaluation of mechanical properties and fracture mode of the samples was assessed using uniaxial tensile test, micro-hardness test and scanning electron microscope (SEM). The results revealed that by increasing number of ECAR passes at a specific temperature, yield strength, ultimate tensile strength and micro-hardness increased in which that increasing rate is more higher at the initial passes than the last ones, while the elongation decreased, contrarily. Study of the mechanical properties of the samples after applying the ECAR process in a specified pass at different temperatures showed that by increasing the temperature, the yield strength, ultimate tensile strength and micro-hardness of samples decreased in comparison with the samples processed in the ambient temperature. However, the elongation was improved. As a quantitatively results, at the end of the third pass at 300°C, the yield strength and micro-hardness of the samples decreased by 14.8% and 8.5%, respectively, in comparison with the samples processed in the ambient temperature, and the elongation increased by 22.2%.

In this study, the effect of tool pin geometry on the mechanical and microstructural changes in the weld region and near it was investigated in the Friction Stir Welding process of butt joint of GOST 4784-97 aluminum alloy, using two types of threaded conical and cylindrical tool pins. To study the microstructure, a metallographic analysis using optical microscope and scanning electron microscope was used, and a tensile and micro hardness tests were used to investigate the effect of pin rotation on the mechanical properties of the joint. The results of the metallographic survey show a smooth and polished surface of the welded specimens with fine threaded cylindrical pin. The EDS analysis indicates the precipitates of aluminum, magnesium, manganese and iron in bright colors and the precipitates of oxygen, magnesium, aluminum, and silicon in the dark colors in the images. The micro-hardness analysis has shown that the highest degree of hardness in the weld region is obtained by coarse threaded cylindrical tool; and its reason was hard mechanical work and high temperature during the welding process, which led to the formation of very fine grains by the dynamic recrystallization mechanism, in the stir region. The tensile strength of all welded specimens was greater than the tensile strength of the base metal; and indicates that there are no imperfections in the welds, as well as an appropriate microstructure in frictional stir welding that improves the mechanical properties of the welded area.

In this paper design and construction of a low-budget non-contact optical measuring device by laser light source with acceptable accuracy of ±0.1mm based on optical triangulation method in structure light technique is presented. Essential tests for analyzing the effect of variation in scanning depth of field and ambient light intensity on the resulted point-cloud accuracy and recognition of the optimum values were carried out. The applied hardware equipment consists of an Arduino board microcontroller, web camera, 5mW laser light source with linear pattern and light intensity measuring sensor GY-30. Also Matlab software is used for proposed technique implementation, as an analyzer for captured data from microcontroller, image processing, point-cloud generation in VRML format. Assessing the accuracy of point cloud models and comparison with reference object is done in Geomagic Qualify software. Results showed the direct impact of studied parameters on final accuracy in thickness measurement, and the necessity of determination of the optimal values.

The effect of size distribution of metal powder particles on the density and strength of fabricated parts under high velocity impact loading has been investigated in this paper. Experiments have been performed on aluminum powder using gas gun apparatus. To do so, pure aluminum powder with three different sizes has been compacted and both density and strength of compacts have been compared. The obtained results show that the coarsest particle size, has the maximum value of density. To evaluate the effect of mixing powder particles with different size distributions on properties of compacts, three initial powders with different weight ratios have been mixed together. The obtained results show that the density of composite part increases as the content of powder with greater particle sizes increases, but this has no particular effect on strength. Next, a mathematical modelling using neural network method has been presented to predict the density of compacts. Through this method, obtained experimental values are used as input by the neural network method. Comparison of values predicted using this model with those obtained by experiments, represents an appropriate level of adjustment.

The Single grit scratch test is one of the first experiments for the fundamental recognition of the behavior of the material and the mechanism of chip formation under the grinding process. In this Test, a grit as an agent of the grinding wheel, is involved with the workpiece. The interpretation of its results makes a significant contribution to the understanding of the grinding behavior of this material, and the mechanism of cutting. Polyether ether ketone has been considered for its unique mechanical and chemical properties in aerospace and medical engineering. One of its applications is the construction of implants in the medical industry. In this study, the effect of uncut chip thickness has been studied on the mechanism of chip formation of the Polyether ether ketone. Several tests were carried out at different depths (starting from 1 μm) and different cutting speed (5, 10 and 15 m/s). By increasing the cutting speed, a higher specific energy is required and the amount of energy at a maximum depth would be 2.5 j/mm3.